This invention relates to improvements in endless printing ribbon cartridges for use in high speed band printers. Recent years have seen the development of such high speed printers, for example of the type used in connection with computer systems or the like. It is among the desirable characteristics of such printers that there be a simple, trouble-free means by which a substantially continuous supply of printing ribbon can be loaded in and fed through the printer. To this end, a number of ribbon cartridges have become available commercially. They have not been free of difficulty and, in some instances, are believed to have seriously interfered with the substantially continuous and high speed operation of the printing device. For example, the printers typically have a pair of drive rollers which are an integral part of the printer mechanism and which are intended to receive and grip the endless ribbon to advance it progressively through the cartridge and then the printer. It is not uncommon for difficulties to be encountered when the cartridge is first inserted into the machine, where the ribbon may not automatically locate itself properly with respect to the drive rollers. As a consequence, the ribbon may not be gripped properly by the drive rollers which may cause the printer and/or cartridge to jam. In addition, it sometimes may occur that even if the ribbon is oriented properly with respect to the drive rollers, the ribbon may wrap about the drive roller in a manner which also causes jamming. In addition, while it is desirable that such cartridges be of inexpensive, low cost construction so that they may be disposable, the devices which have been proposed or used thus far generally are quite complicated which not only adds to the expense of their manufacture but also tends to increase the chance of failure during operation.
In brief, the present invention utilizes an elongate cartridge housing having an inlet end and an outlet end through which the printing ribbon enters and exits. A pair of arms extend from the inlet and outlet ends of the housing, to define a generally U-shaped configuration, and serve to guide the ribbon into and then out of the housing. The ribbon thus extends from the outer end of the arms to define an exposed loop which is utilized in the printer to print the desired characters on the paper. The ribbon advances from the exposed loop, through the arm at the inlet end of the housing and then through a ribbon control assembly to the drive rollers of the printer. The rollers protrude into the interior of the housing when the cartridge is in place on the printer.
The ribbon control assembly includes guide means which assures that the ribbon will always be positioned properly between the drive rollers when the cartridge is initially inserted into the printer as well as during operation of the printer. The control assembly also includes fingers which, when the assembly is shifted to its drive position, wrap about the drive rollers to further guide the ribbon and assure that the ribbon cannot inadvertently be caught by and wrapped about the drive rollers. This contributes materially to the jam-free characteristic of the invention. The control assembly is supported to slide back and forth within the inlet end of the housing in response to operation of the lever in the printer which locks and unlocks the drive rollers.
The outlet end of the body is provided with a mobius loop device which reverts the ribbon so that during each successive external loop, its surfaces will be reversed. The outlet end of the storage chamber is provided with a wall which serves as an outlet end dam and the wall is provided with a slot to guide the ribbon to the mobius loop device. In addition, a restriction is interposed within the storage chamber upstream of the dam to minimize any tendency for the ribbon to become jammed in the region of the dam.
It is among the general objects of the invention to provide an improved ribbon cartridge for a high speed band printer.
A further object of the invention is to provide a ribbon cartridge of the type described which displays a substantially reduced tendency to jam.
Another object of the invention is to provide a ribbon cartridge of the type described in which the cartridge can be inserted into the machine in a manner which assures proper registration of the ribbon with respect to the drive rollers.
A further object of the invention is to provide a ribbon cartridge in which the ribbon cannot fall out of the housing.
Another object of the invention is to provide a ribbon cartridge which is low cost and inexpensive construction and which embodies simple mechanisms, whereby it lends itself to disposable use.